This invention relates to a vibratory core drill apparatus for applying force to a sampling tube for the recovery of soil and sediment samples.
Recent trends in environment monitoring and pollution control have called for core sampling mechanisms which can deliver large diameter uncontaminated sediment and soil land fill profile cores. The fields of agriculture, engineering and mineral exploration also require large diameter undisturbed soil and sediment profile cores for structure and chemical analysis. Representative soil or sediment samples are often required at depths of up to twenty meters of overburden comprising sediments 25-80% solids.
The use of high frequency vibratory core sampling techniques facilitates the collection of sediment cores with minimal disruption of the circumference layer and without serious compaction or dewatering of the sample. Piston or gravity drive sampling systems including split spoons or shelby tubes often fail to deliver undisrupted and representative sediment or soil samples. Wink discloses a vibratory drill apparatus in Canadian Patent No. 1,163,985, but this apparatus suffers from many drawbacks. The Wink drill is hand held and underpowered, therefore the drill has a very limited penetration depth and is awkward to use. The Wink drill vibrates while it is in operation and, being hand held, the vibration of the Wink drill results in trauma to the arms of the operator. Furthermore, the Wink drill yields soil and sediment samples which are not truly representative due to the fact that the operator cannot apply a uniform downward force onto the drill. This ununiform downward force results in bullnosing or collection of an unrepresentative sample due to temporary blockage of the core tube by stiffer material in the sedimentary sequence.
The Wink drill does not permit the coupling and uncoupling of sampling tubes without first disconnecting the vibrator from a flexible power shaft or hydraulic line. This inability makes the operation of such vibratory drill slow, tedious and awkward. Furthermore, this drawback renders the use of a drill stand for mounting and steadying the vibratory drill, as well as a drive means for driving the sampling tube down into the ground, impractical.
Yet another problem with the prior art rested in the vibrators themselves. The amplitude of the vibrations produced by the said vibrators were not adjustable, furthermore, the frequency of vibration produced was difficult to regulate. Said prior art therefore, could not adjust the nature of the vibrations produced by their vibrators to match the soil or sediment conditions. As a result, said prior art yielded lower quality, less representative, soil or sediment samples.
U.S. Pat. Nos. 3,301,336 and 3,352,160, both to Mount disclose vibratory core sampling apparatus suffering many of the above mentioned drawbacks.